Positive-parity baryon spectrum and the role of hybrid baryons
Tanjib Khan, David Richards, Frank Winter
Abstract
We calculate the low-lying spectra for the positive-parity $\mathrm{\ensuremath{\Delta}}$ and $N$ at two pion masses of 358 and 278 MeV using an isotropic clover action with two degenerate light-quark and one strange-quark flavors through the application of the generalized variational method within the distillation framework. The spectrum exhibits the general feature observed in previous calculations using an anistropic clover lattice, with a counting of states at least as rich as the quark model. Furthermore, we identify states that are hybrid in nature, where gluonic degrees of freedom play a structural role, indicating that such states appear as a feature of the excited baryon spectrum, irrespective of the lattice action, or the precise details of the smearing of the lattice interpolating operators used to identify such states.